Other installations using water Drenchers

Question 1

Label the layout of a typical drencher system

Answer 1

Drain valve
Main stop valve
Fire Brigade inlet
Roof drencher
Drencher heads

Question 2

Describe a drencher system

Answer 2

A drencher system is comprised of water heads
somewhat similar to those of sprinklers; these may
be sealed or unsealed (open drenchers), but in the
case the water is turned on manually. In a few
instances drenchers may be controlled by quick opening valves operated by loss of air pressure in a
adjacent premises. The layout of a typical drencher
system is shown in Figure 9.1

Question 3

Drenchers are of three main types:

Answer 3

Roof drenchers;
n Wall or curtain drenchers;
n Window drenchers.

Question 4

Describe a roof drencher

Answer 4

Roof drenchers have a deflector similar to that of a sprinkler head
From the roof ridge they throw a curtain of water upwards
which then runs down the roof
All parts of the
roof and any skylights, windows or other openings
must be protected

Question 5

Describe wall or curtain drenchers. Give an example of use.

Answer 5

Wall or curtain drenchers (Figure 9.2(2)) throw
water to one side only
in the form of
a flat curtain over those openings or portions of a
building most likely to admit fire.
normally every window or opening on top two floors
Those below this level, except the ground floor
and basement, are fitted on every alternate storey
streams
form a water curtain, which must come into contact
with the window 600mm from the top.
A special special
use for this type of drencher is on the stage
side of a theatre proscenium arch to protect the
safety curtain

Question 6

Describe a window drencher

Answer 6

used to protect window openings
placed horizontally level with the top of the
window, with the deflector 100mm from the surface
a jet is
thrown inwards on to the glass near the top of the
window, while two streams are directed at an angle
of 45 degrees to the lower corners.

Question 7

Describe the water supply to a drencher system

Answer 7

1. Connected to an unlimited supply
2. Highest drencher at least 0.34 bar WITH the 50mm drain valve open
3. 1 FB inlet for every 55 heads
4. Inlet fitted with a non return valve

Question 8

Describe the valves of a drencher system regarding location and protection

Answer 8

1. |Accessible
2. On or near ground floor
3. Frost proofed
4. Away from fire risk area
5. Padlocked or strapped in appropriate position
6. Position of drencher controlled by each valve must be marked
7. 1 valve to max of 72 heads

Question 9

What are the stats re spacing of drencher heads

Answer 9

Drenchers fitted on the top row below the eaves
and those on the apex of the roof, must have a
maximum horizontal spacing of 2.5m.
Windows or other openings, or combustible materials in walls exceeding 2.5m in width must be protected by two or more drenchers not more than 2.5m apart, and
not more than 1.25m from the window jambs.
Windows separated by not more than 600mm of
incombustible material may be treated as one window.
Not more than 12 drenchers may be fixed on
any horizontal line of pipe, and not more than six
on one side of the vertical feedpipe.

Question 10

What are the 2 types of drencher discharge

Answer 10

Open or Sealed

Question 11

List the points of an open drencher system

Answer 11

operated simultaneously by the
opening of the main valve
Drain valve is always open unless in use

Question 12

List the points of an sealed drencher system

Answer 12

individually actuated in the same way as a
sprinkler head
normally operate on the alternate system